Human cytomegalovirus (HCMV), a member of the herepesvirus family, is the leading viral cause of birth defects and causes significant morbidity and mortality in immunosuppressed individuals. There is a great need for vaccines that will prevent cytomegalovirus (CMV) associated disease, with the immunization of women before reaching childbearing age being of paramount importance. The major objective of our research is to utilize the murine model to develop a vaccine that will provide sterilizing immuniity and protect fully against both the acute and latent CMV infection. The strategy is to use the technique of DNA vaccination coupled with immunization with inactivated virus to determine which combination of murine cytomegalovirus (MCMV) gene products and route of administration of vaccine will generate the most vigorous and protective immune response against a subsequent parenteral or mucosal viral challenge. We have already completed a number of pilot projects and have made significant progress towards achieving the goals of this project. Our most important accomplishment is that we have developed a vaccine approach that completely protects BALB/c mice from subsequent systemic infection with virulent virus. In this grant application, we propose to accomplish the following 3 aims: 1. Determine the protective efficacy of the dual immunization against mucosal challenge; 2. Determine whether the route of DNA immunization affects protection; and 3. Optimize the vaccination protocol. The long range goals of this research are to elucidate the underlying principles of successful vaccination and apply this information towards the development of a human vaccine.